1. Field
This invention relates to a method for producing a module to be incorporated in a card body wherein a module carrier is provided with a conductive structure on one side. The invention relates in addition to a corresponding module and to a method for incorporating such a module in a card body and a data carrier card having such a module.
2. Related Art
One way of producing data carrier cards that are used for example as identification, credit or debit cards or the like consists in inserting a module containing the actual data carrier and having contact areas for contacting the data carrier in a reading and/or writing device into a specially provided gap in the card body. Such a module generally consists of a “module carrier” or “substrate” having on one side a conductive structure for forming the contact areas. On the other side a chip is usually mounted on the module carrier as a data carrier. The inputs and outputs of the chip are electrically connected with the contact areas through the module carrier. With modules produced at present, the module carrier is usually made of epoxy resin or Kapton and recently also PEN. However, these materials can only be connected adhesively with the card by means of an adhesive layer. A great variety of methods are known for fastening such a module in the gap of the card body by means of an adhesive layer.
Thus, EP 0 521 502 describes a method for incorporating a module in a two-step gap of a card body. First, an annular double-sided contact adhesive element is fastened on the shoulder areas of the deeper gap in the card body. Then, the module is inserted into the gap with the contact areas on the outside, the module being glued in the edge area to the double-sided adhesive element disposed in the shoulder area of the recess.
EP 0 493 738 describes another method for gluing the module to the card body. A thermally activable adhesive layer is positioned on the underside of the module opposite the contact areas. The module is then inserted into the gap of the card body with the adhesive layer and glued by application of heat and pressure.
DE 197 31 737 A1 discloses a method according to the generic part of the independent claims, in particular a method for producing a module to be incorporated in a card body wherein a module carrier is provided with a conductive structure on one side (upper side). In this method, an anchoring element made of a material (e.g. aluminum) having a softening parameter contrary to the material of the card body (e.g. a plastic) is further applied to the underside of the module carrier to which a chip is later applied. This guarantees that when heated the card body softens while the anchoring element remains solid so that it penetrates into an undercut cavity of the card body and can become lodged there.
EP 0 359 632 A1 discloses a further method for producing a module to be incorporated in a card body wherein a module carrier is provided on its underside with anchoring elements that are provided for anchoring in the card body and therefore must not soften.
U.S. Pat. No. 5,851,854 discloses a method for producing a double-layer data carrier with an electronic module wherein a cavity around the module is filled with a material having a low softening temperature. For this purpose the module is disposed in a gap of a first layer so that the cavity remains between the first layer and the module. A second layer is printed in some places with the material having the low softening temperature. The two layers are then assembled so that the material comes to lie on the module. The two layers are then assembled so that the material comes to lie on the module. During subsequent heating, the material softens and penetrates into the cavity between the module and the first layer. This causes the module and the double layer to be glued together.
A disadvantage of these gluing methods is that despite all efforts to find a good adhesive for embedding modules in the card body, this bond always constitutes a weak point. The reason is that the adhesive must enter into a good bond both with the material of the module carrier and with the material of the card body. Since these materials are always different, a compromise must be made when selecting the adhesive.
It is the problem of the present invention to provide an alternative to this stated prior art.
According to the invention, during production of the module carrier a material consisting of thermoplastic whose properties essential for a certain manner of connection, for example thermowelding, with a layer of material of the card body upon incorporation of the module in the card body are adjusted to said relevant layer of material of the card body to the extent that the plastics have a similar softening parameter is used at least for a first layer of the module carrier located on the underside opposite the conductive structure. This permits very simple and reliable welding of the plastics to each other. That is, the ultimately adhesive layer of the module carrier is already applied “inline” during production of the module, and the properties of the connecting layer at the same time adjusted quite specifically to the card material with which the connection is to be entered into, and to the manner of connection.
This adaptation of the layer of the module carrier to be connected with the card body to the material of the card body thus permits an optimal bond to be obtained. Moreover, it permits glueless connection methods such as welding of the plastics, in which methods the quality of the connection depends very importantly on the properties of the materials to be connected. Such glueless connections are especially advantageous since they do without the additional working step of applying the adhesive layer during production of the data carrier cards. This makes the implantation process shorter, which entails considerable cost advantages.
Which softening parameters are specifically involved in the method depends on the particular desired welding technique. Thus, upon application of the thermowelding process the material of the module carrier is selected so that the softening temperatures of the two plastics are equally high if possible. For ultrasonic welding, high-frequency welding or vibration welding, the plastics should soften at similar frequencies.
In an especially preferred example, the module carrier consists on the underside opposite the conductive structure of the same material as the layer of material of the card body to be connected with the module carrier upon incorporation. In this case the properties are not only adjusted to each other, but even identical. Any of the abovementioned welding processes can therefore be used for example for connecting the module with the card body. Adjustment of this kind also has advantages for the conventional manner of connection by means of adhesive, since an adhesive can be selected that is precisely adjusted to this one material, so that no compromise between different materials to be connected must be made with respect to the selected adhesive.
In the simplest example, the module carrier has a single layer. That is, it consists only of a single layer consisting of the specially selected material with the properties adapted to the card body.
Further, the module carrier can also be produced of two layers, so that between the first layer to be connected with the card body and the conductive structure there is a second layer consisting of a material whose properties are again adjusted to the requirements in further processing of the module carrier, e.g. to application of a conductive structure. For this layer the material can be selected for example so that the total module has a certain mechanical stability necessary for later processing. Two-layer module carriers can be produced very simply by the coextrusion technique.
In a further example, these first and second layers are interconnected by at least one connection layer, for example an adhesive layer. In this case, the module carrier thus has at least three layers. Three-layer module carriers can be produced very simply as laminated films.
Preferably, the inventive modules are produced precisely like conventional modules in the form of an endless or continuous module tape. Such a module tape has a module carrier tape to which conductive structures are accordingly applied for a plurality of modules disposed along the module tape. The ultimately connecting layer of the module carrier tape, i.e. the layer opposite the conductive structures, is produced here “inline” during production of the module carrier tape and thus integrated directly into the module carrier tape. This module tape is then further processed like a conventional, known module tape, i.e. for example the chips are applied, the contacting produced and the chips cast by the usual methods. The individual modules are then detached from the module carrier, preferably being punched or cut out.
Such “inline” production of the connection layer in the module tape is possible with a multilayer module carrier tape for example using a coextrusion technique. As an alternative, such a multilayer module carrier tape can be produced by a laminating technique, i.e. in the form of an endless laminated film tape. This method is recommendable in particular for the production of module carrier tapes having connection layers between the individual functional layers of material, i.e. for the three- or multilayer version.